When talking about Du Bois and The Souls of Black Folk, you should mention this, from his introduction to the 50th anniversary edition:

"I still think today as yesterday that the color line is a great problem of this century. But today I see more clearly than yesterday that back of the problem of race and color, lies a greater problem which both obscures and implements it: and that is the fact that so many civilized persons are willing to live in comfort even if the price of this is poverty, ignorance, and disease of the majority of their fellowmen; that to maintain this privilege men have waged war until today war tends to become universal and continuous, and the excuse for this war continues largely to be color and race."